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From: Jason Gunthorpe <jgg-uk2M96/98Pc@public.gmane.org>
To: Devesh Sharma <devesh.sharma-dY08KVG/lbpWk0Htik3J/w@public.gmane.org>
Cc: linux-rdma <linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
	Doug Ledford <dledford-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
	Leon Romanovsky <leon-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Subject: Re: [PATCH v1 rdma-core 1/2] bnxt_re/lib: fix the memory barrier call during poll-cq
Date: Fri, 10 Nov 2017 10:30:46 -0700	[thread overview]
Message-ID: <20171110173046.GD17451@ziepe.ca> (raw)
In-Reply-To: <CANjDDBggw1wKuyh6OobsxPpe1U7esnFgD9evCoTYDV2FvnjTTQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>

On Fri, Nov 10, 2017 at 05:01:42PM +0530, Devesh Sharma wrote:

> > And the the kernel version of this should be using READ_ONCE()
> 
> Okay, we will fix this in our driver. So, READ_ONCE(CQE.valid) should
> be enough right?

Yes, I think so.

> > In user space we should probably create a
> >
> >  udma_from_device_read_once(x)
> >
> > That incorporates the barrier and the 'access_once' semantics..
> 
> Do you want us to pull all the defined in kernel space compiler.h
> verbitum to rdma-core

No.. kernel is using a quite different approach. We would want to use
C11 atomic_read in user space for most architectures.

Jason
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  parent reply	other threads:[~2017-11-10 17:30 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-11-09 11:10 [PATCH v1 rdma-core 0/2] libbnxt_re bug fixes Devesh Sharma
     [not found] ` <1510225840-20034-1-git-send-email-devesh.sharma-dY08KVG/lbpWk0Htik3J/w@public.gmane.org>
2017-11-09 11:10   ` [PATCH v1 rdma-core 1/2] bnxt_re/lib: fix the memory barrier call during poll-cq Devesh Sharma
     [not found]     ` <1510225840-20034-2-git-send-email-devesh.sharma-dY08KVG/lbpWk0Htik3J/w@public.gmane.org>
2017-11-09 18:05       ` Jason Gunthorpe
     [not found]         ` <20171109180521.GM7063-uk2M96/98Pc@public.gmane.org>
2017-11-10 11:31           ` Devesh Sharma
     [not found]             ` <CANjDDBggw1wKuyh6OobsxPpe1U7esnFgD9evCoTYDV2FvnjTTQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2017-11-10 17:30               ` Jason Gunthorpe [this message]
2017-11-09 11:10   ` [PATCH v1 rdma-core 2/2] bnxt_re/lib: increment psn in case of 0 length packets Devesh Sharma
2017-11-09 11:54   ` [PATCH v1 rdma-core 0/2] libbnxt_re bug fixes Leon Romanovsky

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